1. Field of the Invention
The present invention relates to a method of flip-chip mounting a semiconductor chip that bonds a semiconductor chip to a substrate at low temperature and a mounting apparatus that uses the same method.
2. Related Art
Among typical methods of flip-chip mounting a semiconductor chip to a substrate, there is a method that bonds a semiconductor chip onto a substrate by applying a thermosetting resin to the substrate, positioning and disposing the semiconductor chip on the substrate from above the thermosetting resin, and applying pressure to the semiconductor chip using a bonding tool while applying heat to thermoset the thermosetting resin. There is also a method that bonds the semiconductor chip to the substrate more strongly by having the bonding tool also apply ultrasonic vibration to the semiconductor chip to combine metal parts using ultrasound.
When ultrasonic bonding is carried out, there is also a method that fills, after the semiconductor chip has been bonded using ultrasound, a space between the semiconductor chip and the substrate with thermosetting resin (post-filling with underfill resin) and then applies heat to set the thermosetting resin. When this method is used, during the bonding of the semiconductor chip to the substrate using ultrasound, ultrasonic bonding is carried out while the ambient temperature is heated to a substantially equal temperature to the heating temperature (around 150° C.) of the thermosetting resin. In this way, heating is also carried out during bonding using ultrasound firstly to increase the bonding force, and also to make the thermal contraction that occurs between the members during ultrasonic bonding and the thermal contraction that occurs due to the thermal effect of the thermosetting resin as equal as possible and thereby prevent detachment of the bonded parts.
Each of the conventional methods of bonding a semiconductor chip described above requires a heating step, so that there is the problem that large-scale equipment is needed. Also, since the coefficients of thermal expansion of the semiconductor chip and the substrate are different, there is a further problem that positional displacement can easily occur between both parts, thereby reducing the positional accuracy of the bonding of the semiconductor chip.
Japanese Laid-Open Patent Publication No. 2001-308145 discloses a method of mounting that places a semiconductor chip with bumps on a substrate with pads onto which an underfill adhesive has been applied and applies heat and ultrasonic vibration using a bonding tool to bond the bumps and pads, wherein during the application of heat and ultrasound, UV rays are irradiated to harden a surrounding part of the adhesive that has been pressed outward between the semiconductor chip and the substrate.
However, in the above method of mounting, although the surrounding part of the adhesive is hardened by irradiation with UV rays, the UV rays do not reach the adhesive between the semiconductor chip and the substrate which remains unhardened, resulting in the problem that a step that completely hardens the adhesive by applying heat has to be carried out at an appropriate time afterwards.
Patent Document 1
Japanese Laid-Open Patent Publication No. 2001-308145
As described above, there have been the problems of a heating device being required in each of the conventional methods of mounting, resulting in an increase in the scale of the equipment, and of reduced positional accuracy for the mounting.